Moderate amounts of alcohol consumed may have similar protective effects on depression to those that have been observed for coronary heart disease, researchers said.

Few studies have looked at the relationship between mental health and moderate alcohol intake.

Researchers report on a cohort study that followed over 5,500 light-to-moderate drinkers for up to seven years. The results show an inverse relationship between alcohol intake and incidence of depression.

The study participants were aged between 55 and 80 years old, and had never suffered from depression or had alcohol-related problems when the study started.

Their alcohol consumption, mental health and lifestyles were followed for up to seven years through yearly visits, repeated medical exams, interviews with dietitians and questionnaires.

The main alcoholic beverage drunk by the study participants was wine. When analysed, it was shown that those who drank moderate amounts of wine each week were less likely to suffer from depression.

The lowest rates of depression were seen in the group of individuals who drank two to seven small glasses of wine per week. These results remained significant even when the group adjusted them for lifestyle and social factors, such as smoking, diet and marital status.

"Lower amounts of alcohol intake might exert protection in a similar way to what has been observed for coronary heart disease. In fact, it is believed that depression and coronary heart disease share some common disease mechanisms," Professor Miguel A Martinez-Gonzalez, from the University of Navarra (Spain), senior author of the paper, said.

Previous studies have indicated that non-alcoholic compounds in the wine, such as resveratrol and other phenolic compounds, may have protective effects on certain areas of the brain. The study was published in the journal BMC Medicine.